In data visualization systems, events may be displayed on a timeline to enable a user to get an overview of a plurality of events. On a timeline, a particular time duration is represented by a corresponding line segment. The events are positioned on the timeline according to the time associated with each event. The user of the visualization system may set the time window, or the time interval shown on the time line, to view a particular time period on the timeline canvas.
In some practical applications, for example a clinical informatics application, a user, such as a physician, could have a need to make a detailed comparison of several periods in a patient's medical history. These periods can be visualized on a timeline.
“Intelligent visualization and exploration of time-oriented data of multiple patients”, by D. Klimov et al, in Artificial Intelligence in Medicine, 49 (2010) pp. 11-31, discloses an interactive, ontology-based exploration module, which enables the user to visualize raw data and abstract concepts for multiple patient records, at several levels of temporal granularity. An absolute, calendar-based timeline and a relative time line are disclosed. The relative time line is set by identifying clinically significant events which serve as a date of reference (time zero) for all patient data. The data of all patients is aligned according to the reference time point. The data values shown on the absolute timeline are quite different from the data values on the relative timeline, because all values and statistics are recalculated according to the new zero point. In the calendar-based timeline, the absolute dates or months are displayed along the timeline. In the relative timeline, the number of days or months from the reference time point are displayed along the timeline. In either case, the data for a plurality of patients are shown as a graph on a single timeline.